Load sensor element and manufacturing method of load sensor element

Abstract

A load sensor element includes a substrate made of a ceramic material; an inorganic layer having a surface configured to receive a load, the inorganic layer covers a portion of the substrate; a thin-layer resistance body whose resistance value changes in accordance with the load received by the inorganic layer, the thin-layer resistance body having a main body portion and a pair of end portions, the main body portion mounted on the covered portion of the substrate and sandwiched between the substrate and the inorganic layer, the pair of end portions mounted on an exposed portion of the substrate, and the exposed portion free of the inorganic layer; and a pair of electrodes electrically connected to the pair of end portions of the thin-layer resistance body and separated away from the inorganic layer and on one side of the substrate.

The invention claimed is: 
     
       1. A load sensor element configured to detect a load, the load sensor element comprising:
 a substrate made of a ceramic material or a metal material, the metal material having an insulating layer on its surface; 
 an inorganic layer having a pressure receiving surface configured to receive the load, the inorganic layer being provided so as to cover a part of a single surface of the substrate; 
 a thin-layer resistance body formed of a resistance body whose resistance value is changed in accordance with the load received by the inorganic layer, the thin-layer resistance body having a main body portion and both end portions, the main body portion being sandwiched between the substrate and the inorganic layer, the both end portions being mounted on an exposed portion of the substrate, and the exposed portion of the substrate being not covered with the inorganic layer; and 
 a pair of electrodes electrically connected to the both end portions of the thin-layer resistance body so as to be separated away from the inorganic layer, the electrodes being provided on one side of the substrate, wherein 
 the inorganic layer is made of a ceramic substrate, and 
 a thickness of the inorganic layer is from 0.3 mm to 5.0 mm, inclusive. 
 
     
     
       2. The load sensor element according to  claim 1 , wherein the inorganic layer is made of the ceramic substrate, the inorganic layer being provided on the main body portion via a bonding layer. 
     
     
       3. The load sensor element according to  claim 1 , wherein
 a thickness of the substrate is from 0.3 mm to 5.0 mm, inclusive. 
 
     
     
       4. The load sensor element according to  claim 1 , wherein
 the thin-layer resistance body is made of a NiCr material or a Cr material. 
 
     
     
       5. The load sensor element according to  claim 1 , wherein
 a thickness of the thin-layer resistance body is greater than 0 and 1 μm or less. 
 
     
     
       6. The load sensor element according to  claim 1 , wherein
 the main body portion is formed of a meandering patterned portion. 
 
     
     
       7. The load sensor element according to  claim 6 , wherein the both end portions have: electrode connecting portions on which the pair of electrodes are respectively provided; and connecting portions configured to connect the meandering patterned portion with the electrode connecting portions. 
     
     
       8. The load sensor element according to  claim 1 , wherein
 both of the substrate and the inorganic layer have a rectangular shape. 
 
     
     
       9. The load sensor element according to  claim 1 , wherein
 the substrate has a circular shape, and 
 the main body portion is formed of an arc-shaped meandering patterned portion or an arc-shaped patterned portion following an external contour of the substrate. 
 
     
     
       10. The load sensor element according to  claim 1 , further comprising:
 a positioning part provided so as not to interfere with the main body portion, the positioning part being configured to position the load sensor element. 
 
     
     
       11. A manufacturing method of a load sensor element according to  claim 1 , the manufacturing method comprising:
 a step of preparing a substrate layer made of a ceramic material or a metal material, the metal material having an insulating layer on its surface; 
 a step of laying a thin-layer resistivity layer on the substrate layer and laying an electrode layer on the thin-layer resistivity layer; 
 a step of forming a plurality of electrodes by performing a patterning of the electrode layer; 
 a step of forming a plurality of thin-layer resistance bodies by performing a patterning of the thin-layer resistivity layer, the thin-layer resistance bodies having main body portion and both end portions on which the pair of electrodes are to be respectively mounted; 
 a step of forming a load sensor element plate by laying an inorganic layer body such that the plurality of main body portions are covered in such a manner that the inorganic layer body is separated away from the electrodes, the load sensor element plate having a plurality of cell elements on which the pair of electrodes are provided, and the inorganic layer body being formed of a plurality of continuous inorganic layers corresponding to a number of the main body portions; and 
 a step of splitting the load sensor element plate into the plurality of cell elements.